Krzysztof Tadyszak

Small-diameter vascular grafts that can grow with pediatric patients and resist thrombosis remain an unmet need, primarily due to slow and unstable endothelialization. Here, we engineer a tri-layer, human induced pluripotent stem cell (hiPSC)-derived vascular graft featuring a soft, patterned lumen. We introduce a scalable soft-lithography method to imprint longitudinal micro-grooves directly into the lumen of compliant hydrogel tubes, a key advance for cell-laden constructs. Computational fluid dynamics reveals that these grooves redistribute wall shear stress into protective low-shear valleys and aligning high-shear ridges without increasing the mean load. This engineered shear landscape, combined with a bioactive elastin-like recombinamer (ELR) hydrogel matrix, synergistically enhances hiPSC-endothelial cell (hiPSC-EC) capture and retention under perfusion. Patterned grafts accelerate the formation of confluent, axially aligned endothelial monolayers with mature VE-cadherin junctions, outperforming non-patterned controls. Concurrently, smooth muscle cells within the graft wall deposit extracellular matrix, driving time-dependent mechanical maturation. This platform provides a physiologically relevant model for vascular disease and a promising strategy for engineering growth-competent pediatric grafts.

Extensive peripheral nerve injuries often lead to the loss of neurological function due to slow regeneration and limited recovery over large gaps. Current clinical interventions, such as nerve guidance conduits (NGCs), face challenges in creating biomimetic microenvironments that effectively support nerve repair. The developed GrooveNeuroTube is composed of hyaluronic acid methacrylate and gelatin methacrylate hydrogel, incorporating active agents (growth factors and antibacterial agents) encapsulated within an NGC conduit made of 3D-printed PCL grid fibers. In vitro studies showed that GrooveNeuroTube significantly promoted migration of dorsal root ganglion (DRG) neuronal cells, 3D bioprinted at the far ends of the conduit to imitate a proximal nerve injury as a novel ex vivo model. A long-term culture of up to 60 d was employed to better mimic in vivo conditions. This model tested the effects of pulsed electromagnetic field stimulation on neural tissue development. After 60 d, GrooveNeuroTube showed a 32% cell migration increase compared to the growth-factor-group and 105% compared to the no-growth-factor condition. These results confirm that the GrooveNeuroTube system can effectively support sustained neural cell migration and maturation over extended periods, proving a new technology for testing peripheral nerve injury ex vivo.

Extensive peripheral nerve injuries often lead to the loss of neurological function due to slow regeneration and limited recovery over large gaps. Current clinical interventions, such as nerve guidance conduits (NGCs), face challenges in creating biomimetic microenvironments that effectively support nerve repair. The developed GrooveNeuroTube is composed of hyaluronic acid methacrylate and gelatin methacrylate hydrogel, incorporating active agents (growth factors and antibacterial agents) encapsulated within an NGC conduit made of 3D-printed PCL grid fibers. In vitro studies showed that GrooveNeuroTube significantly promoted migration of dorsal root ganglion (DRG) neuronal cells, 3D bioprinted at the far ends of the conduit to imitate a proximal nerve injury as a novel ex vivo model. A long-term culture of up to 60 days was employed to better mimic in vivo conditions. This model tested the effects of pulsed electromagnetic field (PEMF) stimulation on neural tissue development. After 60 days, GrooveNeuroTube showed a 32% cell migration increase compared to the growth-factor-group and 105% compared to the no-growth-factor condition. These results confirm that the GrooveNeuroTube system can effectively support sustained neural cell migration and maturation over extended periods, proving a new technology for testing peripheral nerve injury ex vivo . Graphical The graphical abstract was created with BioRender.com.

Synthesis and characterization of lithium phthalocyanine radicals were performed, which were followed by an investigation on its ability to detect oxygen levels in biologically relevant concentrations. EPR studies confirmed the presence of at least two phases, one sensitive to oxygenation (γ-phase) and the second one insensitive to oxygenation (α-phase). Contrary to the findings reported in the literature, it was observed that the γ-phase was not stable at and above 95 °C and slowly transformed into the α-phase crystallographic structure. Above 150 °C, only a broad signal of α-phase existed. Additional characterizations were performed using electrochemical impedance spectroscopy (EIS), cyclic voltammetry, dynamic light scattering (DLS), and Raman spectroscopy on pristine crystals Li₂Pc and LiPc sensors.

The performed research presents modeling results for designing microfluidic vortex diodes. These devices rectify fluid flow and can be used in many applications on micro and macro scales. The modeling, utilizing computational fluid dynamics (CFD) with the turbulence model RANS k-ε in COMSOL Multiphysics, has led to optimizing diodicity—the reversed-to-forward flow pressure drop ratio. The goal was to find the best flow-rectifying geometry within the 2D vortex-type design by changing the wall geometry, diode shape, and inflow velocities, identifying significant parameters and dependencies. Improving diodicity can be achieved by increasing the radius r₁ of the central channel, increasing the entire diode radius r₂, decreasing the width w of the rectangular channel, and reducing its length L. Additionally, changing the circular shape of the diode to an elliptical one can improve diodicity. The significance of this research is evident in the potential applications of these devices in microfluidic setups where fixed-geometry unidirectional flow is required, e.g., mixing, filtration, cell separation, and drug delivery, or on industrial scales, e.g., energy harvesting, wastewater treatment, and water sterilization.

We report applying the autoclaved hydrothermal method for obtaining conductive reduced graphene oxide (rGO) fibers for potential flexible electronic applications, such as supercapacitors, transistors, or sensing applications. The reduction of GO was performed in the temperature range 120 to 180 °C under increased pressure of ca. 8 bar in a sealed Teflon lined up, stainless steel autoclave. The fiber’s diameter and length were defined by the glass tube used as the mold for reducing GO water suspension (diameter of 600 µm and length of 8 cm). After drying, in an ambient atmosphere, the hydrogel fiber shrinks to ca. 50 µm in diameter and 6 cm in length (collapsed pore structure). The drying process, in addition to enhancing electrical conductivity, also increases the mechanical strength of the fibers due to the stronger overlapping of the graphene flakes. The best performance was observed in the fiber reduced at the highest temperature studied, 180 °C, and a minimum temperature of 120 °C is necessary to obtain a fiber. Electrical conductivity was measured using the 4-probe method. The results were analyzed within the framework of variable range hopping and Arrhenius models to pinpoint the best model describing electrical conductivity in dry rGO fibers.

A new method for the preparation of polyaniline (PANI) films that have a 2D structure and can record high active mass loading (up to 30 mg cm⁻²) via acid-assisted polymerization in the presence of concentrated formic acid was developed. This new approach represents a simple reaction pathway that proceeds quickly at room temperature in quantitative isolated yield with the absence of any byproducts and leads to the formation of a stable suspension that can be stored for a prolonged time without sedimentation. The observed stability was explained by two factors: (a) the small size of the obtained rod-like particles (50 nm) and (b) the change of the surface of colloidal PANI particles to a positively charged form by protonation with concentrated formic acid. The films cast from the concentrated suspension were composed of amorphous PANI chains assembled into 2D structures with nanofibrillar morphology. Such PANI films demonstrated fast and efficient diffusion of the ions in liquid electrolyte and showed a pair of revisable oxidation and reduction peaks in cyclic voltammetry. Furthermore, owing to the high mass loading, specific morphology, and porosity, the synthesized polyaniline film was impregnated by a single-ion conducting polyelectrolyte-poly(LiM_n-r-PEGM_m) and characterized as a novel lightweight all-polymeric cathode material for solid-state Li batteries by cyclic voltammetry and electrochemical impedance spectroscopy techniques.

This article focuses on EPR relaxation measurements in various carbon samples, e.g., natural carbons—anthracite, coal, higher anthraxolites, graphite; synthetically obtained carbons—glassy carbons, fullerenes, graphene, graphene oxide, reduced graphene oxide, graphite monocrystals, HOPG, nanoribbons, diamonds. The short introduction presents the basics of resonant electron spin relaxation techniques, briefly describing the obtained parameters. This review presents gathered results showing the processes leading to electron spin relaxation and typical ranges of electron spin relaxation rates for many different carbon types.